Hi Cameron, As far as I can tell, you have an error in your syntax. You're using a - (hyphen) character in the first match, but Regex uses this to define a range of characters. It seems that if you don't escape it, the whole thing behaves a little strangely. For example, using your URL as the source string: http://www.domain.com/path1/path2.php?PHPSESSID=2u0ccaffoh6jaeapkke35qpp87; This regular expression /^(http:\/\/www\.domain\.com([\/\.\-\_\w]*))/ matches [!MATCH!]?PHPSESSID=2u0ccaffoh6jaeapkke35qpp87; and this /^(http:\/\/www\.domain\.com([\/\.-\_\w]*))/ matches the whole URL The only difference is the hyphen has been escaped in the first expression. I'm not sure if this will help any, but it's definitely something I noticed in the regex. Ash www.ashleysheridan.co.uk
--- Begin Message ---
- To: <php-general@xxxxxxxxxxxxx>
- Subject: Negative Look Ahead Regex - Code Mistake or Bug?
- From: "Cameron B. Prince" <cplists@xxxxxxxxxxxxxxxxxx>
- Date: Sun, 17 Aug 2008 17:55:34 -0500
- Delivery-date: Sun, 17 Aug 2008 23:55:56 +0100
- Envelope-to: ash@xxxxxxxxxxxxxxxxxxxx
- Thread-index: AckAvFsom/qg7AtHQUiTg8E3ny5z1A==
- Thread-topic: Negative Look Ahead Regex - Code Mistake or Bug?
- User-agent: Microsoft-Entourage/12.1.0.080305
Hello, I¹ve run into a problem with a regex and need help determining if this is my mistake or a bug. The regex is for inserting a SID into every link in the buffer before it¹s flushed, but only when each link doesn¹t already have a SID. An example of the code is here: $buffer = preg_replace('/"http\:\/\/www\.domain\.com([\/\w\.-]*)(?!\?PHPSESSID\=2u0cca ffoh6jaeapkke35qpp87;?)/', '"http://www.domain.com$1?PHPSESSID=t9gksvpdcuobsnqt98qloe6lg4;', $buffer); The code works correctly in most cases except when a SID already exists and there is a path after the .com such as: http://www.domain.com/path1/path2.php?PHPSESSID=2u0ccaffoh6jaeapkke35qpp87; When this URL is processed by the regex, it becomes: http://www.domain.com/path1/path2.ph?PHPSESSID=t9gksvpdcuobsnqt98qloe6lg4;p? PHPSESSID=2u0ccaffoh6jaeapkke35qpp87; So the problem is the regex not only falsely matches, it's inserting the SID in between 2nd and 3rd letters of the extension. You can see the code in action here: http://kottmann.com/test.php The full source for the test code is also available when viewing the source of this page. I've tested this on PHP v5.1.6 and PHP v5.2.6. TIA, Cameron -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
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